ROCHESTER — After a public hearing, the City Council approved increases to the water and sewer rates on Tuesday.

Ratepayers will see their water rates go up by an average of 2.4 percent, with the new water rate being $4.60 per 100 cubic feet of water. Sewer rates have increased by 2.2 percent on average. The new sewer rate is $6.24 per 100 cubic feet of water.

According to Mayor T.J. Jean, the rate increases do not take into account the anticipated costs associated with having to make multimillion dollar upgrades to the city’s wastewater treatment plant, in light of the Environmental Protection Agency being expected to implement a stringent permit limit on the amount of nitrogen that can be discharged from the plant.

Currently, the wastewater treatment plant discharges more than 20 milligrams per liter of nitrogen. Recently, the EPA issued a permit limit to Newmarket, which limits that amount to 3 milligrams per liter, and Rochester is expected to receive the same limit sometime in the future, according to city officials.

If the 3 milligram per limit permit comes to light in Rochester, the city could face $15.1 million to $19.7 million in capital costs of having to do substantial upgrades to the wastewater treatment plant.

“It would be, in my opinion, catastrophic to sewer rate payers,” said Jean after Tuesday’s meeting.

He said that sewer rates would most likely double over time if a 3 milligram per liter permit is implemented, by which point sewer rate payers could end up paying $1,200 more per year on their sewer bills.

But Jean noted that Rochester has not yet received a draft nitrogen permit, which would be issued by the EPA before the actual permit limit is issued.

Jean said the city did not want to raise sewer rates substantially before knowing more certainly that multimillion dollar upgrades would actually be required by the EPA.

The increases to the water and sewer rate that were passed on Tuesday, said Jean, is to increase the fund balance of the water and sewer funds, which will be used to pay for already approved water- and sewer-based capital improvement projects.

These projects include the reconstruction of Brock Street, Salmon Falls Road, and Pine Street.

With the increased rates, Rochester residents paying both water and sewer rates will see their combined bills increase by an average of $28 per year, according to Finance Director Blaine Cox, who is also a deputy city manager.

While the Utility Advisory Board presentation on the new rates made to the council in September highlighted the anticipated EPA permit limit, Jean said Tuesday the increases to the water and sewer rate would likely be the same this year even without the upcoming permit.

During Tuesday’s public hearing, city resident Robert Goldstein was concerned the rate increases might snowball and prove to be burdensome on ratepayers. Goldstein, past chairman of the Utility Advisory Board, said the city should look at increasing revenues across the board rather than just increasing the water and sewer rates. He suggested the council also look at potentially increasing the hookup costs and service charges.

Resident and state Rep. Fred Leonard, who opposed the increases during the public hearing, said the city should consider outsourcing its water and sewer operations to be more effective and save money.

“I don’t think it’s fair to the taxpayer if you don’t put everything on the table,” said Leonard, who said a nitrogen permit of 3 milligrams per liter would be “extremely traumatic” to sewer rate payers.

Increases to both water and sewer rates were approved by the council 8-2 on Tuesday. Councilors Ralph Torr and David Walker voted against both of the increases. Councilors Julien Savoie, Alan Reed-Erickson and Stephen Hervey were not present at the meeting.